Yearly Archives: 2015

Holiday DIY: Crystal Chemistry

Crystals may seem like a geologic scientific mystery…until you see them grow in your own kitchen! Here is what you will need:


  • Wide mouth jars or cups
  • Pipe Cleaners (You can also use coffee filter paper or experiment with other materials. Even white paper works okay)
  • String
  • Popsicle sticks (Pencils work too!)
  • Borax
    • Note: Borax is a mild skin irritant. Nothing here necessitates touching it, but wearing gloves can be a good precaution, especially if you have sensitive skin. Definitely wear gloves during cleanup!
  • A pot of water and a stove

Step 1: Start by making whatever shape you want to crystalize out of pipe cleaner. This will be the base for the crystals to grow on. You can try using other materials too!  We tried to go for holiday themed shapes, but it is important to note that we are not artists!


Step 2: Use a string to tie your creation to the popsicle stick. Then set the popsicle stick over the top of the jar so the pipe cleaner masterpiece hangs about an inch or higher from the bottom (some of the ones in the picture below are too low!). Don’t worry too much about the length of string, if it is too long, just twist the popsicle stick to raise it!

hanging holidays

Step 3: Get the water hot on the stove. It needs to be close to, or even boiling. Add borax and stir it in until it disappears. Repeat this until you start to see Borax on the bottom of the pot. It can dissolve a LOT, so don’t be shy. The amount will also depend entirely on the amount of water. The water may get too cloudy to see the bottom, so use a spoon to check instead.


Step 4: At this point, just pour your mixture carefully into the jar with the pipe cleaner suspended inside. For more festive results, now is a great time to add a few drops of food coloring. Crystals should start to form within an hour. For big crystals, let them go overnight!

Once they are ready, grab the popsicle stick and pull them out! Depending on how much borax you got to dissolve in the solution in step 3 and how long you left the crystals to grow, the amount of crystallization that you get can be radically different. Feel free to experiment! After all, this is science!

Pro Tip: For cleanup, be careful disposing of the leftover borax solution. It could crystalize in your drain in the same way. To prevent this from happening, just run hot water as you slowly pour it out.

Now let’s take a look at what was happening and why this whole thing works! Ever notice that you can dissolve more sugar in hot tea than iced tea? Warm liquids can handle greater concentrations of dissolved substances than those at room temperature. These mixtures are called supersaturated, and they’re very unstable– it doesn’t take much to re-separate their ingredients as they cool. Given something to attach to, the molecules suspended in a supersaturated solution will begin clumping together in crystals.



Glow Stick Science

Glow sticks are chemical reactions waiting to happen! Most are made of an outer plastic casing with a small glass capsule inside. The outer tube is filled with dye, which determines the color of the glow stick, and a chemical called diphenyl oxalate. The glass within contains hydrogen peroxide, the same thing you might use to clean out a cut or scrape.


When you crack a glow stick, you break the glass inside. Its ingredients are then free to mix and react, releasing carbon dioxide and chemical energy, which is converted to visible light. The reaction takes some time, which is why the glow lasts a while. The ratio of compounds in a glow stick determines whether it shines brightly and briefly or more dimly for a long time.

Temperature is another great way to control chemical reaction speed. When we add energy by heating up the glow stick reactants, the molecules move faster and interact more often. Cooling the system takes energy away, literally slowing things down at a microscopic level. Clear containers of cold, warm, and boiling water give a great view of this chemical property!

The fourth flask, on the far left, contains liquid nitrogen. At -321 degrees Fahrenheit, this cryogenic substance is so cold that it actually stops the luminescent reaction, making the glow sticks go dark. We can bring them back to life by allowing them to absorb energy in a warmer environment.


Bang, Pow! Collision Science

When cars, billiard balls, or football players collide, their momentum doesn’t just disappear. It has to go somewhere. Some collisional energy dissipates as heat, and some causes the incoming objects to recoil. Take a basketball hitting the ground. Both the ball and the ground become a little warmer than they were before. The basketball also deforms, storing elastic potential energy, which changes into kinetic energy as the ball pushes off and launches back into the air.


When a ball hits the ground, its center of mass keeps moving down for as long as the ball’s elasticity allows. As a result, the ball is vertically squished for a moment before it bounces back up. Image credit:

The heavier a thing is, the more momentum it has in motion. Inertia depends on mass, too: the lighter an object is, the easier its motion is to change. When a bug hits a car windshield, the bug’s path changes dramatically, while the car is almost completely unaffected. The bug’s inertia and momentum are comparatively small, so the dynamics of the collision are dominated by the car’s movement. The same science applies when we drop a stack of bouncy balls of various sizes.


At first, all three balls move together towards the ground. When the basketball makes contact, it stretches and deforms, then reverses direction, putting it on a collision course with the next object in the stack. The basketball is much more massive than its neighbor, so its motion dominates when they crash into each other. Unlike a bug and a windshield, however, the balls don’t stick together. Instead, the basketball’s momentum is transferred to the smaller ball.


Momentum is directly related to both mass and velocity. If momentum is held constant, then when mass goes down, velocity goes up. The smaller, lighter ball is launched with impressive speed! Adding a third, even smaller component to the system compounds the effect.

Into Thin Air: CO2 Science

Carbon dioxide, or CO2, is one of the handful of compounds that most people are familiar with. People and animals breathe it out, plants love it, and we make a lot of it, which probably has some consequences. We are going to look at this well known gas in its solid form and hopefully answer any questions that come up along the way!

bigbubbs croppedSolid carbon dioxide is more often referred to by the name dry ice. This is because it never leaves behind a wet spot when it disappears. Unlike water, which will melt to a liquid naturally under normal conditions at room temperature, dry ice will instead skip to a gas. To the left, you can see dry ice under water releasing bubble after bubble of transparent carbon dioxide gas. This physical transition from a solid to a gas is called sublimation, and isn’t anything to be afraid of. Its just the less familiar cousin of evaporation and condensation. For more on that, check out this blog.

Here, we put our dry ice in a bowl of warm water. Water is constantly evaporating, and this warm water is no exception. As a result, the air above the water is very humid as it contains a lot of this evaporated water. One important thing about dry ice that hasn’t been mentioned yet: it’s cold. Like -109℉ cold. Brrr!

Adding it to the water causes air temperature to drop, forcing the water vapor in the air to condense. If it looks like fog, that’s because it is! We have simply made a low-flying cloud in a bowl! Clouds in real life form the same way. Warm air carries water vapour up into the high, cold parts of the atmosphere where they condense in the same way, minus the dry ice, of course.

The cloud forming is independent from the bubble expanding. This is a bit tricky. As the water vapor cools down and condenses it is not pushing out on the bubble. However, the dry ice is sublimating. the resulting carbon dioxide gas takes up more space. Unfortunately, CO2 is colorless. This makes it look like the cloud is blowing up the bubble, but really the cloud is just filling up the space that the sublimated dry ice is clearing out for it, until…

burst my bubble

The bubble bursts and the dense cloud falls to the ground, which looks really cool. It also raises a rather interesting question: If clouds are more dense than air, then what in the world are they doing way up there in the sky? The answer is a bit complex. The short version is that the tiny water droplets that make up clouds fall very slowly, but they tend to form in warm, rising, low pressure air that overcomes their slow fall, allowing them to float high in the sky.

For more information, I recommend reading this article.

Diffusion, Pizza, and You

If you were to take a freshly baked pizza and put you and it at opposite ends of a vault with no airflow at all, would you ever be tempted by its delicious aroma? The answer, it turns out, is yes! Even without the aid of air currents, the smell would spread. Nothing in the room appears to be moving, but at the molecular level, things are very different.

At room temperature, the molecules in stagnant air whiz around at insane speeds– over 1000 miles per hour! The air seems still because molecules are so light that nobody can feel them individually, and there are approximately equal amounts of them going in every direction. However, tiny particles (like the delicious pizza odor) can still get knocked around by these randomly moving molecules. The process of stuff spreading out due to the movement of tiny molecules is called diffusion.

Molecule TempThe experiment you see in the video has one obvious difference: we are looking at a liquid instead of a gas. The molecules in water are much more tightly packed, and unlike in a gas, there isn’t as much room for them to zoom around. This means the molecules aren’t moving at such incredible speeds, but they also aren’t sitting still. They bump into one another, rotate, and vibrate like crazy!

Diffusion in ActiojnThe amount of spinning, bouncing, and vibrating that they do depends on one thing: temperature. In fact, temperature is really just a way to measure how energetic the molecules are. In the container of warmer water, the food coloring spreads more quickly. This is because at higher temperatures, the more vigorous vibrating and bouncing of the molecules pushes the green food coloring around faster. The cooler water has calmer molecules, which do less to disturb the blue food coloring.

Notice that the food coloring never seems to regroup together. Diffusion is entirely based on random movements of huge numbers of molecules, so it always results in concentrated areas of stuff like the food coloring spreading out to fill the available area. This trend towards uniform distribution is called entropy.


Diffusion causes molecules to spread out from areas of high concentration to areas of low concentration. Image credit: UC Davis

Random movement of tiny things may seem inconsequential, but it’s actually incredibly important. It’s how plants hydrate, hot chocolate cools down, spaghetti noodles absorb water, and even how oxygen gets to the bloodstream. Even more important than all of that however, is that it lets you know when there is pizza nearby!

What is a Black Hole?

You’ve probably heard of black holes, those mysterious cosmic vacuum cleaners that tear apart and suck up everything around them. These exotic objects make for excellent science fiction and have a reputation for being incredibly complicated. While they can live up to their complex reputation, at a basic level they are actually not too difficult to wrap your head around!


The black hole from the blockbuster Interstellar, which hired astrophysics guru Kip Thorne as a consultant to keep scientific accuracy through much of the movie.

rocket19Jumping up in the air on Earth is a short-lived journey. An average person starts their upward flight with a speed of about 7 miles per hour. Our planet’s gravity quickly overwhelms that momentum, and the jumper lands. However, if someone could jump at 25,000 miles per hour, they could escape Earth’s gravitational pull and continue into space! Every planet and star has a special speed requirement to escape its gravity. We call this speed the escape velocity. Larger objects have higher escape velocities; it would take a monstrous 133,000mph takeoff to break free of Jupiter’s gravitational pull. The sun would shut down any jump slower than 1.4 million mph!

A black hole has so much gravity that not even light, the fastest thing in the universe, can escape it. Light travels at a whopping 670,000,000 mph. As we have seen, the bigger the planet or star, the faster something has to go to overcome its gravity. So black holes must be HUGE, right? Well, sort of.

SparkfunEverything you have ever seen on Earth is made out of atoms. While many people are aware that atoms are made up of protons, neutrons, and electrons, it might be more accurate to say they are made up of nothing. The most common atom in the universe is hydrogen. It is made up of one proton and one electron and is 99.9999999996% completely empty space. To think of it another way, if a hydrogen atom were the size of our planet, the proton would be just over a tenth of a mile wide, the electron would be about three inches across, and they would be separated by about 4000 miles. Most of our universe is empty!

Classic diagram of an atom. All of the parts are drawn FAR too large, which makes sense because if they were to scale they would all be too small to see! Image credit: Sparkfun

Black holes have a LOT of mass, which is why they have so much gravity. So much, in fact, that atoms are actually crushed to fill in the empty space. Sometimes a dying star has enough mass (and gravity) to crush atoms, but not quite enough to keep light from escaping. In these cases, a neutron star is born. These strange objects contain as much mass as the sun, but are squeezed into a space smaller than New York City. Put another way, a soup can of the stuff would weigh about as much as the mountain that AstroCamp lives on!

TahquitzBlack holes are so massive that not even light can break free from their gravity. Inside a black hole, the immense gravitational pull crushes atoms and even neutrons themselves down into a tiny speck called a singularity. This tiny point of matter is even smaller than an atom. It can range tremendously in mass, from about twice as heavy as the sun for a smaller black hole, to millions of times the mass of the sun!

Everything that we know about space comes from the light that galaxies and stars and other things give off. However, black holes don’t let light escape, so how do we find them? Well, there are a couple of ways. One is to wait for the black hole to get in between us and a distant object. Since gravity can bend light, this results in gravitational lensing, where the black hole distorts images of the things behind it, a bit like a carnival mirror.

Grav Lens

Simulation of a black hole causing gravitational lensing on the Milky Way. Note that it is not actually moving the stars, just bending the light to change how we see it! Credit: Andrew Hamilton

The black hole at the center of our galaxy was found another way: by looking at how stars in its neighborhood are moving. They whiz around in circles as if pulled by an immense central object, but we can’t see anything there. Calculating the mass needed to move the stars that fast reveals the invisible culprit: a black hole! See for yourself:
Sag A

Tabletop Rockets Science

Temperature is a measure of energy. Adding energy to a substance makes it hotter; removing energy makes it colder. Warm, energetic molecules move faster and farther, spreading out over a larger volume of space.


This balloon has been cooled to hundreds of degrees below zero (Fahrenheit), condensing the gas molecules inside. At room temperature, the condensed gas spreads out and expands, stretching the balloon back out to its original size!

We can make a gas less dense by heating it up. Less dense substances float in denser substances. This is how hot air balloons work! The warm gas inside is thinner and lighter than the air outside, so the balloon rises up through the thicker, heavier air around it. In this experiment, we’ll harness the temperature-dependence of density to turn ordinary tea bags into miniature rockets.


Step 1: Cut the staple, string, & folded paper away from the top of the tea bag. Step 2: Empty & unfold the bag to form a cylinder. Step 3: Ignite the rocket from the top.

Tea bags work well for this demonstration because they’re light, flammable, and conveniently shaped.  Emptying and unfolding the bag yields an open-ended cylinder. As the delicate paper burns, the air inside the cylinder heats up and becomes less dense. At the same time, some of the tea bag is converted to smoke, leaving a super-light skeleton of ash behind. Takeoff occurs when the structure becomes so light– and the air inside so thin– that the rocket is, overall, less dense than the air around it.

WARNING: flaming tea bags follow unpredictable flight patterns. If you try this experiment at home, be sure to choose a non-flammable setting, and keep a fire extinguisher handy.

Happy Thanksgiving 2015

Everyone knows that on Thanksgiving you eat lots of turkey and it makes you sleepy somehow…except that it probably doesn’t. There is a lot of information out there about this subject, and much of it seems to disagree with itself. Let’s examine the whole idea from the beginning.

Thanksgiving celebration and dinner

Thanksgiving celebration and dinner

Courtesy of Rutgers University

It all starts with proteins, which are large molecules that facilitate a tremendous number of different functions within living organisms like humans. Proteins are kind of like words, except instead of being made up of letters, they are built from amino acids. There are twenty different amino acids, and they make up the protein alphabet. By putting these in different sequences, proteins can be varied just like words with different combinations of letters. However, unlike words that might be ten letters long, the average protein in humans is just under 500 amino acids in length*!

One of these amino acids is called tryptophan, and it can be found in turkey! This particular amino acid is involved in a biochemical pathway that produces serotonin, which in turn produces  is often associated with positive emotions, where melatonin helps the body keep up with the day-night cycle by anticipating darkness and contributing to feelings of sleepiness. So far so good! Turkey has tryptophan and tryptophan turns into something that makes you sleepy!



The problem is that turkey doesn’t have very much tryptophan. Most amino acids come from food, and many foods have much more tryptophan than the delicious main course for Thanksgiving. Some have suggested that the unique combination of tryptophan-filled turkey and carbohydrates on Thanksgiving could help enable the tryptophan-to-melatonin pathway. While there may be some truth to this, cheddar cheese contains more tryptophan than turkey and a grilled cheese sandwich would meet the same requirement, yet somehow nobody seems to have heard of the Great Grilled Cheese Nap-ternoon Effect [not a real thing].

Tryptophan Chart

Common foods tryptophan contents compared to turkey. Source: (see above)

Still, many people can anecdotally recall just how tired they are on Thanksgiving, and this whole myth had to come from somewhere. There are likely a few contributing factors which are admittedly a little less fun and definitely sound less cool and scientific. First of all, people often feel fatigued after lunch as their bodies turn their attention to digestion, a phenomenon not unique to the holiday feast. In addition, everyone hears about how tired Thanksgiving should make them, which leads to something called the placebo effect, essentially making people tired because they think they should be.  On top of that, Thanksgiving often has the wonderful effect of bringing families together…which results in lots of travel, cleaning, discussion, cooking, and football without a lot of time for sleep. Sounds like a great recipe for a tired afternoon.

Happy TG JPL

AstroCamp Staff visiting JPL earlier this year!

*How Big is the Average Protein,


The Speed of Fire

How fast is fire? We sent a burst of flame through a fluorescent light tube to explore the propagation of an alcohol-burning reaction along an enclosed path. In our experiment, the frontier of flame sped along at over six feet per second. Fire behaves very differently in other environments. In space, combustion becomes almost unrecognizable.


Gif: SpaceFire1

Flames speed along the tube, rebounding at each end.

Fire heats the air around it, causing molecules to speed up and spread out. On Earth, warm air rises as the cooler, thicker surrounding atmosphere sinks towards the base of the flames. This current delivers fresh oxygen to the base of the fire, and it continues burning for as long as the fuel supply lasts. In space, there’s not enough gravity to pull the cold air down, so flames burn spherically. Without the pull of a convection current, oxygen isn’t carried to the source of the reaction; instead, it diffuses into the fire. Random motion of air molecules isn’t a very efficient way to bring oxygen and fuel together, so flames in microgravity burn out much more quickly than we’re used to seeing here on Earth.


In microgravity, flames are shaped like spheres instead of teardrops. This color image is from the FLEX (Flame Extinguishment) experiment on the ISS. Image credit: NASA/GRC

Fire is a serious hazard on a spacecraft because there’s nowhere to escape to. Reliable fire-extinguishing technology is a vital part of safe, sustainable space travel. Strategies that work well on Earth, however, don’t always do the trick hundreds or thousands of miles above its surface– new tactics are required. In the last several years, combustion experiments on the ISS have begun to reveal the mysterious and fascinating behavior of fire in microgravity.

A few years ago, scientists studying space combustion noticed something phenomenal going on after their experimental flames died out: the fuel kept burning. No visible light was emitted, and the reaction was much cooler — around 700 degrees Fahrenheit instead of the usual 2500 or so — but the fuel burned away nonetheless. This behavior isn’t usually observed on Earth, but if we can find a way to replicate it consistently, it could be used for applications such as low-emission auto engines.


A droplet of heptane fuel burns in microgravity in this false-color time-lapse image. The droplet appears yellow and becomes smaller as it burns. Green areas are initial soot structures. Image credit: NASA

Microgravity research is already yielding exciting knowledge about the nature of fire outside of Earth’s influence, and there’s much more to come. Dr. Forman Williams, UC San Diego, is one of the investigators working on the FLEX-2 experiment to demystify space combustion. In 2013, he summed up the state of the field: “when it comes to fire, we’re just getting started.”

The Circle of Electromagnetism














